1. Field of the Invention
The present invention relates generally to wheeled luggage cases, and more particularly, to a carry-on luggage case of the type known as a flight bag having wheels on a bottom wall of the case and a retractable handle for pulling the case along on the wheels. The flight bag includes an externally mounted, removable carrying case for securely transporting a delicate instrument such as a laptop computer.
2. Discussion of the Prior Art
"Flight bag" type luggage cases including wheels and a retractable handle for convenient storage in aircraft overhead storage bins are well known; see, e.g., U.S. Pat. No. 5,253,739 on a wheeled flight bag with a retractable pull handle and U.S. Pat. No. 5,566,797 on a wheeled integrated flight bag and garment bag luggage case, the entire disclosures of which are incorporated herein by reference.
Flight bags have enhanced the convenience of travel but the wheels and handle are only useful for transporting the flight bag itself and not the other articles a traveler may need to carry. As a result, many flight bag users have resorted to attaching second bags or other articles of luggage to a flight bag using rope, elastic cords (e.g. `bungee` cords), tape and other temporary attachments which may not actually support and retain the second bag during the strenuous handling often encountered in commercial travel.
Luggage manufacturers have provided a more elegant solution to the problem faced by flight bag users wanting to carry a second bag by incorporating retractable luggage attaching straps, such as shown in U.S. Pat. No. 5,593,009. The retractable strap attachments can be attached to the second bag in any number of ways but do not securely bind the second bag to the flight bag; instead, the strap attachments merely provide a hook from which the second bag may hang, (e.g. by the second bag's handle). In addition, if a valuable article such as a portable computer is to be carried in the second bag, a retractable strap cannot be used to securely lock the second bag onto the flight bag.
Travelers often use "Laptop" and "Notebook" portable personal computers having reduced size and weight. Unfortunately, it is difficult to manufacture a compact portable computer which is rugged enough to withstand being dropped or otherwise subjected to shock loading. The small size of today's portable computers leaves little or no internal room for shock absorbing materials to protect the vulnerable operating parts of the computer such as the LCD screen, the hard drive, the mother board with its various electrical connectors or the plastic outer case.
The effect of being dropped or hit is measured in acceleration terms; one unit of gravitational acceleration (1 G) represents an acceleration (or deceleration) of 32 feet/sec.sup.2. Each computer manufacturers design is unique, so there is no universally safe level of shock for portable computers. Computer hard drive manufacturers claim hard drives will typically withstand shocks in the range of 75 to 200 g. Manufacturers of LCD screens, on the other hand, typically guarantee their screens to withstand shocks of only 50 g, a level reached by dropping a portable computer from a height of approximately six inches. Since carrying cases or luggage for portable computers are usually hand held, hung from shoulder straps or affixed to flight bags at heights substantially greater than six inches, cases designed to carry and protect computers must provide adequate protection against falls from these greater heights.
Most manufacturers of carrying cases for portable computers incorporate foam padding into their cases; the padding typically ranges in thickness from a half inch to three inches. Foam padding will protect a computer, unless the padding is compressed completely (e.g., compressed to half the original thickness). Thus, three inches of padding will protect the computer through a deceleration distance of only one and one-half inches. Tests have shown that in carrying cases provided with two inches of foam padding, the 50 G threshold (for LCD screens) is exceeded in drops from heights of as little as eight inches. Portable computer carrying cases offering superior protection against shocks are disclosed in U.S. Pat. No. 5,217,119, to W. Dale Hollingsworth (applicant in the present application), U.S. Pat. No. 5,524,754, to W. Dale Hollingsworth and patent application Ser. No. 09/235,292, filed Jan. 22, 1999, also to W. Dale Hollingsworth; the entire disclosures of U.S. Pat. Nos. 5,217,119, 5,524,754 and patent application Ser. No. 09/235,292 are incorporated herein, in their entireties, by reference.
If a traveler carrying a flight bag also has a portable computer carried in a second bag, bungee cords, retractable straps and tape cannot be relied on to securely attach the second bag to the flight bag since, as discussed above, the resulting combination is not well suited to rough handling, even if the second bag is the finest computer carrying case.
Others have offered a somewhat better solution to the problems confronting traveling computer users, at least insofar as attaching the computer carrying case is concerned. The Targus company offers a flight bag called the "Targus Shuttle" in which a computer case is carried entirely within a flight bag compartment and accessed by opening a zip-down flap opening into the flight bag compartment. A traveling computer user must open the flight bag zip-down flap and remove the computer carrying case from within the compartment in the flight bag, then close the flight bag zip-down flap for flight bag stowage; a sequence of steps requiring the traveler to set the computer carrying case aside somewhere while closing the flight bag zip-down flap.
Often, a computer user traveling with a portable computer on an airplane is confronted by conflicting needs. When boarding and before take-off, the computer user must quickly stow any carry-on luggage in an available overhead compartment, hanging closet or under-seat space. The airplanes aisles are often narrow, cramped and crowded with other impatient travelers who are struggling to fill the rapidly diminishing overhead compartments with their own carry-on luggage or hurrying to find and occupy their seats. Often, a computer user wants to use his or her portable computer during the flight. Problems arise if the computer user has packed the portable computer in a flight bag which must now be quickly stowed in the overhead compartment before all available space is depleted by others, or before other travelers trying to reach their seats lose patience. If the computer user stands in the aisle, opens the flight bag, removes the portable computer and then closes the flight bag, tempers may flare. The only other choice is to quickly stow the flight bag and later try to retrieve the flight bag from a packed overhead compartment to unpack the computer while en-route.
There is a need, then, for a luggage system that confers the benefits of a flight bag but does not penalize the computer user who needs a protective computer carrying case and ready, convenient access to the computer.